import * as proto from './extend'
let _vue
function setProto (obj) {
  Object.keys(obj).forEach(item => {
    _vue.prototype['$' + item] = obj[item]
  })
}
export default function install (Vue) {
  if (install.installed && _vue === Vue) return
  install.installed = true
  _vue = Vue
  setProto(proto)
}
